1. Field of the Invention
This invention relates to cycloheptenols and their derivatives, products therefrom, methods for their use, and methods of synthesis thereof. In particular, the invention provides a convenient synthesis of substituted cycloheptenols and their derivatives and compositions, methods for their use, and articles prepared using the compounds, products and compositions. The compounds are particularly suited for fragrance applications.
2. Background
The use of some organic compounds as fragrance ingredients has been investigated and documented in the literature. In particular, some organic compounds and their derivatives have been used to enhance and improve the aroma of a number of articles, which include fine perfumes, soaps and detergents.
U.S. Pat. No. 3,546,279 discloses the conversion of 5,7-dimethyl-1,6-octadiene to an ester of 3,3,5-trimethyl cycloheptanol by reacting the diene with an acid such as formic acid or acetic acid in the presence of an acid catalyst. This catalyst can be a Lewis acid such as boron trifluoride, aluminum chloride, and stannic chloride, or strong mineral acids like sulfuric or phosphoric acid. Hydrolysis of the ester with water in the presence of an alkali metal hydroxide generated 3,3,5-trimethyl cycloheptanol. Oxidation of the alcohol with aluminum isopropoxide in cyclohexanone, potassium dichromate, or chromic acid produced the ketone.
Using a similar procedure as described above, Hall et al. (J. Org. Chem. 1972, 37, 920), disclosed the cyclization of 5,7-dimethyl-1,6-octadiene and 3,7-dimethyl-1,6-octadiene with formic acid in the presence of a Lewis acid catalyst. Hydrolysis of the formate esters to generate the corresponding cycloheptanol followed by oxidation to produce the ketone was also disclosed.
The two references cited above disclose that substituted cycloheptanols and its derivatives, where the seven-member ring is completely saturated, can be used as fragrance ingredients. The present invention describes the synthesis of substituted cycloheptenols and its derivatives, where a unit of unsaturation has been introduced into the ring or, if saturated, it is a bicyclo compound. The starting material 2,4-dimethyl-2,7-octadien-4-ol, which is a by-product made in the pyrolysis of 2-pinanol as disclosed in U.S. Pat. No. 3,240,821 herein incorporated in its entirety by this reference, is available in significant quantity. Until now, no valuable commercial products have been generated from 2,4-dimethyl-2,7-octadien-4-ol. Substituted cycloheptenols and its derivatives are readily available from 2,4-dimethyl-2,7-octadien-4-ol using the present invention. These compounds also possess fragrant aromas, and can be used to confer, enhance, improve, or modify the odor of an article.
Additional advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the appended claims. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed.